A 61-year-old Japanese woman who was an HTLV-1 carrier had angioimmunoblastic lymphadenopathy with dysproteinemia (AILD)-like dysplasia that transformed into AILD-type lymphoma after 3 years. Complete remission was achieved with interferon-alpha (IFN-alpha) treatment following a previous combination of anticancer drugs. IFN-alpha was also effective for maintenance therapy after this complete, albeit transient, remission. From clinical and pathological studies on AILD patients, it appears that AILD may in some cases be the consequence of an immune dysfunction caused by HTLV-1 infection and that AILD-type lymphoma is a malignant disorder of peripheral T cell clones different from those T cells incorporating the HTLV-1 virus.